THE ALPHA AND BETA-THYROID RECEPTORS ARE EXPRESSED BY CULTURED EPENDYMAL CELLS - CORRELATION WITH THE EFFECT OF L-3,5,3'-TRIIODOTHYRONINE ON GLUTAMINE-SYNTHETASE MESSENGER-RNAS

It is generally accepted that L-3,5,3'-triiodothyronine (L-T3) acts at the genomic level through an interaction with specific nuclear L-T3 receptors (NT3R). Using antibodies raised against different peptides of NT3R, we report here the immunocytochemical localization of the alpha, alpha2, beta1 NT3R subtypes in ependymal cell primary cultures. The alpha and beta thyroid hormone receptors are both expressed. While the alpha and alpha2 subtypes are found in almost all cells, the beta1 receptors are present in few cells only. The possibility that alpha and beta receptors are colocalized is discussed. We also demonstrate that ependymal cells respond to L-T3 with a marked increase of the expression of the glutamine synthetase messenger RNAs.